This invention relates to a catalyst.
PCT/GB 94/00321 discloses a catalyst for use in the oxidation of carbon monoxide and hydrxcarbons which comprises a porous alumina support having captured thereon a complex comprising gold, a transition metal selected from cobalt and manganese, and the alumina, the concentration of gold on the support being less than 2 percent by mass of the catalyst, and the arornic ratio of gold to transition metal being in the range 1:30 to 1: 200. Of these catalysts, the preferred catalyst is one which has cobalt as the transition metal. The alumina is said to have a large surface area, typically 80 to 400m.sup.2 /g.
PCT/GB 95/02566 tiscloses a catalyst comprising an oxide support selected from zirconium oxide, cerium oxide and mixtures thereof having captured thereon a noble metal in catalytically effective form. Preferably the noble metal is gold and there is also present a transition metal oxide having a spinel structure, e.g. cobalt oxide or ferric oxide, with the gold being associated with the transition metal oxide. This catalyst is also suitable for catalysing the oxidation of carbon monoxide and hydrocarbons and also reducing hazardous nitrous oxides.